The present invention relates to the field of light supports. It finds particular application in conjunction with an adjustable lighting assembly for use in operating theaters, dental surgeries, and the like, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to a wide variety of supported lighting applications.
Jointed supports are commonly used for positioning surgical lights in hospital operating rooms, dental surgeries, and the like to illuminate surgical sites on patients. The support is used to suspend one or more lightheads from a ceiling or wall mount and allows the lighthead to be moved in plural degrees of freedom within the operating room to various positions. It is desirable for the arm of the support to counterbalance the associated lighthead when the lighthead is in any position within a range of positions. A spring is typically carried by the arm to assist in balancing the arm. However, the arm often tends to drift over time, and the light head moves out of position. Additionally, the spring is not able to fully compensate for differences in the forces which occur when the arm is positioned in different angular orientations.
The present invention provides a new and improved adjustable progressive joint brake system and method of use, which overcome the above-referenced problems and others.
In accordance with one aspect of the present invention, a system for movably positioning a piece of equipment relative to an examination site is provided. The system includes a first arm portion and a second arm portion directly or indirectly connected with the piece of equipment. A joint interconnects the first arm portion and the second arm portion. The joint includes a first housing member connected with the first arm portion and a second housing member connected with the second arm portion. A bearing is interposed between the first and second housing members. A clamping assembly clamps the first and second housing members on the bearing with sufficient force to provide a linear brake force on the bearing. A spring arm mechanism applies a radial brake force on the bearing which varies according to the position of the second arm portion.
In accordance with another embodiment of the present invention, an arm assembly is provided. The arm assembly includes first and second arm portions and a joint for positioning the second arm portion in a range of rotational orientations relative to the first arm portion. The joint includes a bearing and first and second opposed housing members which apply a first braking force to the bearing. A spring arm mechanism is connected with the joint and is at least partially received in the second arm portion. The spring arm applies a second braking force to the bearing in a direction generally at right angles to the clamping force. The second bearing force is variable, dependent on the rotational orientation of the second arm portion relative to the first arm portion.
In accordance with another embodiment of the present invention, a method of balancing an arm portion of an arm assembly is provided. The arm assembly includes a joint having first and second relatively rotatable housing members spaced by a bearing. The arm portion is connected to the second housing member. The method includes applying a clamping pressure between the housing members and the bearing in a first direction to create a constant braking force which resists rotation of the second housing member relative to the first housing member. The method further includes applying a variable clamping pressure between at least one of the housing members and the bearing in a direction generally perpendicular to the first direction to provide a variable braking force which resists rotation of the second housing member relative to the first housing member, the variable clamping pressure varying according to the relative rotational positions of the first and second housing members.
One advantage of at least one embodiment of the present invention is that it enables a spring arm to remain in place in a defined position, even when the center of gravity of a light to which it is attached moves.
Another advantage of at least one embodiment of the present invention is that it enables a brake system to be adjusted to generate a varying brake force.
Another advantage of at least one embodiment of the present invention is that a spring arm is optimally adjusted by a combination of spring tension and brake action, allowing the spring arm to be set to any position within a range of angular positions.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.